refactor: moves code related to AST from rule.utils into astutils package (#1380)

Modifications summary:

* Moves AST-related functions from rule/utils.go to astutils/ast_utils.go (+ modifies function calls)
* Renames some of these AST-related functions
* Avoids instantiating a printer config at each call to astutils.GoFmt
* Uses astutils.IsIdent and astutils.IsPkgDotName when possible

internal/astutils/ast_utils.go

@@ -2,8 +2,12 @@
 package astutils
 
 import (
+	"bytes"
+	"fmt"
 	"go/ast"
+	"go/printer"
 	"go/token"
+	"regexp"
 	"slices"
 )
 
@@ -78,9 +82,80 @@ func getFieldTypeName(typ ast.Expr) string {
 	}
 }
 
-// IsStringLiteral returns true if the given expression is a string literal, false otherwise
+// IsStringLiteral returns true if the given expression is a string literal, false otherwise.
 func IsStringLiteral(e ast.Expr) bool {
 	sl, ok := e.(*ast.BasicLit)
 
 	return ok && sl.Kind == token.STRING
 }
+
+// IsCgoExported returns true if the given function declaration is exported as Cgo function, false otherwise.
+func IsCgoExported(f *ast.FuncDecl) bool {
+	if f.Recv != nil || f.Doc == nil {
+		return false
+	}
+
+	cgoExport := regexp.MustCompile(fmt.Sprintf("(?m)^//export %s$", regexp.QuoteMeta(f.Name.Name)))
+	for _, c := range f.Doc.List {
+		if cgoExport.MatchString(c.Text) {
+			return true
+		}
+	}
+	return false
+}
+
+// IsIdent returns true if the given expression is the identifier with name ident, false otherwise.
+func IsIdent(expr ast.Expr, ident string) bool {
+	id, ok := expr.(*ast.Ident)
+	return ok && id.Name == ident
+}
+
+// IsPkgDotName returns true if the given expression is a selector expression of the form <pkg>.<name>, false otherwise.
+func IsPkgDotName(expr ast.Expr, pkg, name string) bool {
+	sel, ok := expr.(*ast.SelectorExpr)
+	return ok && IsIdent(sel.X, pkg) && IsIdent(sel.Sel, name)
+}
+
+// PickNodes yields a list of nodes by picking them from a sub-ast with root node n.
+// Nodes are selected by applying the selector function
+func PickNodes(n ast.Node, selector func(n ast.Node) bool) []ast.Node {
+	var result []ast.Node
+
+	if n == nil {
+		return result
+	}
+
+	onSelect := func(n ast.Node) {
+		result = append(result, n)
+	}
+	p := picker{selector: selector, onSelect: onSelect}
+	ast.Walk(p, n)
+	return result
+}
+
+type picker struct {
+	selector func(n ast.Node) bool
+	onSelect func(n ast.Node)
+}
+
+func (p picker) Visit(node ast.Node) ast.Visitor {
+	if p.selector == nil {
+		return nil
+	}
+
+	if p.selector(node) {
+		p.onSelect(node)
+	}
+
+	return p
+}
+
+var gofmtConfig = &printer.Config{Tabwidth: 8}
+
+// GoFmt returns a string representation of an AST subtree.
+func GoFmt(x any) string {
+	buf := bytes.Buffer{}
+	fs := token.NewFileSet()
+	gofmtConfig.Fprint(&buf, fs, x)
+	return buf.String()
+}

rule/atomic.go

@@ -5,6 +5,7 @@ import (
 	"go/token"
 	"go/types"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -76,9 +77,9 @@ func (w atomic) Visit(node ast.Node) ast.Visitor {
 			broken := false
 
 			if uarg, ok := arg.(*ast.UnaryExpr); ok && uarg.Op == token.AND {
-				broken = gofmt(left) == gofmt(uarg.X)
+				broken = astutils.GoFmt(left) == astutils.GoFmt(uarg.X)
 			} else if star, ok := left.(*ast.StarExpr); ok {
-				broken = gofmt(star.X) == gofmt(arg)
+				broken = astutils.GoFmt(star.X) == astutils.GoFmt(arg)
 			}
 
 			if broken {

rule/confusing_naming.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -190,7 +191,7 @@ func (w *lintConfusingNames) Visit(n ast.Node) ast.Visitor {
 		// Exclude naming warnings for functions that are exported to C but
 		// not exported in the Go API.
 		// See https://github.com/golang/lint/issues/144.
-		if ast.IsExported(v.Name.Name) || !isCgoExported(v) {
+		if ast.IsExported(v.Name.Name) || !astutils.IsCgoExported(v) {
 			checkMethodName(getStructName(v.Recv), v.Name, w)
 		}
 	case *ast.TypeSpec:

rule/confusing_results.go

@@ -3,6 +3,7 @@ package rule
 import (
 	"go/ast"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -28,7 +29,7 @@ func (*ConfusingResultsRule) Apply(file *lint.File, _ lint.Arguments) []lint.Fai
 
 		lastType := ""
 		for _, result := range funcDecl.Type.Results.List {
-			resultTypeName := gofmt(result.Type)
+			resultTypeName := astutils.GoFmt(result.Type)
 
 			if resultTypeName == lastType {
 				failures = append(failures, lint.Failure{

rule/constant_logical_expr.go

@@ -4,6 +4,7 @@ import (
 	"go/ast"
 	"go/token"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -40,7 +41,7 @@ func (w *lintConstantLogicalExpr) Visit(node ast.Node) ast.Visitor {
 			return w
 		}
 
-		subExpressionsAreNotEqual := gofmt(n.X) != gofmt(n.Y)
+		subExpressionsAreNotEqual := astutils.GoFmt(n.X) != astutils.GoFmt(n.Y)
 		if subExpressionsAreNotEqual {
 			return w // nothing to say
 		}

rule/context_as_argument.go

@@ -5,6 +5,7 @@ import (
 	"go/ast"
 	"strings"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -28,7 +29,7 @@ func (r *ContextAsArgumentRule) Apply(file *lint.File, _ lint.Arguments) []lint.
 		// Flag any that show up after the first.
 		isCtxStillAllowed := true
 		for _, arg := range fnArgs {
-			argIsCtx := isPkgDot(arg.Type, "context", "Context")
+			argIsCtx := astutils.IsPkgDotName(arg.Type, "context", "Context")
 			if argIsCtx && !isCtxStillAllowed {
 				failures = append(failures, lint.Failure{
 					Node:       arg,
@@ -40,7 +41,7 @@ func (r *ContextAsArgumentRule) Apply(file *lint.File, _ lint.Arguments) []lint.
 				break // only flag one
 			}
 
-			typeName := gofmt(arg.Type)
+			typeName := astutils.GoFmt(arg.Type)
 			// a parameter of type context.Context is still allowed if the current arg type is in the allow types LookUpTable
 			_, isCtxStillAllowed = r.allowTypes[typeName]
 		}

rule/context_keys_type.go

@@ -5,6 +5,7 @@ import (
 	"go/ast"
 	"go/types"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -51,15 +52,7 @@ func (w lintContextKeyTypes) Visit(n ast.Node) ast.Visitor {
 
 func checkContextKeyType(w lintContextKeyTypes, x *ast.CallExpr) {
 	f := w.file
-	sel, ok := x.Fun.(*ast.SelectorExpr)
-	if !ok {
-		return
-	}
-	pkg, ok := sel.X.(*ast.Ident)
-	if !ok || pkg.Name != "context" {
-		return
-	}
-	if sel.Sel.Name != "WithValue" {
+	if !astutils.IsPkgDotName(x.Fun, "context", "WithValue") {
 		return
 	}
 

rule/datarace.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"go/ast"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -111,7 +112,7 @@ func (w lintFunctionForDataRaces) Visit(node ast.Node) ast.Visitor {
 			return ok
 		}
 
-		ids := pick(funcLit.Body, selectIDs)
+		ids := astutils.PickNodes(funcLit.Body, selectIDs)
 		for _, id := range ids {
 			id := id.(*ast.Ident)
 			_, isRangeID := w.rangeIDs[id.Obj]

rule/defer.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"go/ast"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -106,7 +107,7 @@ func (w lintDeferRule) Visit(node ast.Node) ast.Visitor {
 			w.newFailure("return in a defer function has no effect", n, 1.0, lint.FailureCategoryLogic, deferOptionReturn)
 		}
 	case *ast.CallExpr:
-		isCallToRecover := isIdent(n.Fun, "recover")
+		isCallToRecover := astutils.IsIdent(n.Fun, "recover")
 		switch {
 		case !w.inADefer && isCallToRecover:
 			// func fn() { recover() }
@@ -122,7 +123,7 @@ func (w lintDeferRule) Visit(node ast.Node) ast.Visitor {
 		}
 		return nil // no need to analyze the arguments of the function call
 	case *ast.DeferStmt:
-		if isIdent(n.Call.Fun, "recover") {
+		if astutils.IsIdent(n.Call.Fun, "recover") {
 			// defer recover()
 			//
 			// confidence is not truly 1 because this could be in a correctly-deferred func,

rule/enforce_map_style.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"go/ast"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -101,8 +102,7 @@ func (r *EnforceMapStyleRule) Apply(file *lint.File, _ lint.Arguments) []lint.Fa
 				return true
 			}
 
-			ident, ok := v.Fun.(*ast.Ident)
-			if !ok || ident.Name != "make" {
+			if !astutils.IsIdent(v.Fun, "make") {
 				return true
 			}
 

rule/enforce_repeated_arg_type_style.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"go/ast"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -130,8 +131,8 @@ func (r *EnforceRepeatedArgTypeStyleRule) Apply(file *lint.File, _ lint.Argument
 				if fn.Type.Params != nil {
 					var prevType ast.Expr
 					for _, field := range fn.Type.Params.List {
-						prevTypeStr := gofmt(prevType)
-						currentTypeStr := gofmt(field.Type)
+						prevTypeStr := astutils.GoFmt(prevType)
+						currentTypeStr := astutils.GoFmt(field.Type)
 						if currentTypeStr == prevTypeStr {
 							failures = append(failures, lint.Failure{
 								Confidence: 1,
@@ -163,8 +164,8 @@ func (r *EnforceRepeatedArgTypeStyleRule) Apply(file *lint.File, _ lint.Argument
 				if fn.Type.Results != nil {
 					var prevType ast.Expr
 					for _, field := range fn.Type.Results.List {
-						prevTypeStr := gofmt(prevType)
-						currentTypeStr := gofmt(field.Type)
+						prevTypeStr := astutils.GoFmt(prevType)
+						currentTypeStr := astutils.GoFmt(field.Type)
 						if field.Names != nil && currentTypeStr == prevTypeStr {
 							failures = append(failures, lint.Failure{
 								Confidence: 1,

rule/enforce_slice_style.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"go/ast"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -117,8 +118,7 @@ func (r *EnforceSliceStyleRule) Apply(file *lint.File, _ lint.Arguments) []lint.
 				return true
 			}
 
-			ident, ok := v.Fun.(*ast.Ident)
-			if !ok || ident.Name != "make" {
+			if !astutils.IsIdent(v.Fun, "make") {
 				return true
 			}
 

rule/error_naming.go

@@ -6,6 +6,7 @@ import (
 	"go/token"
 	"strings"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -56,7 +57,7 @@ func (w lintErrors) Visit(_ ast.Node) ast.Visitor {
 			if !ok {
 				continue
 			}
-			if !isPkgDot(ce.Fun, "errors", "New") && !isPkgDot(ce.Fun, "fmt", "Errorf") {
+			if !astutils.IsPkgDotName(ce.Fun, "errors", "New") && !astutils.IsPkgDotName(ce.Fun, "fmt", "Errorf") {
 				continue
 			}
 

rule/error_return.go

@@ -3,6 +3,7 @@ package rule
 import (
 	"go/ast"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -21,7 +22,7 @@ func (*ErrorReturnRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure
 		}
 
 		funcResults := funcDecl.Type.Results.List
-		isLastResultError := isIdent(funcResults[len(funcResults)-1].Type, "error")
+		isLastResultError := astutils.IsIdent(funcResults[len(funcResults)-1].Type, "error")
 		if isLastResultError {
 			continue
 		}
@@ -29,7 +30,7 @@ func (*ErrorReturnRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure
 		// An error return parameter should be the last parameter.
 		// Flag any error parameters found before the last.
 		for _, r := range funcResults[:len(funcResults)-1] {
-			if isIdent(r.Type, "error") {
+			if astutils.IsIdent(r.Type, "error") {
 				failures = append(failures, lint.Failure{
 					Category:   lint.FailureCategoryStyle,
 					Confidence: 0.9,

rule/errorf.go

@@ -6,6 +6,7 @@ import (
 	"regexp"
 	"strings"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -47,7 +48,7 @@ func (w lintErrorf) Visit(n ast.Node) ast.Visitor {
 	if !ok || len(ce.Args) != 1 {
 		return w
 	}
-	isErrorsNew := isPkgDot(ce.Fun, "errors", "New")
+	isErrorsNew := astutils.IsPkgDotName(ce.Fun, "errors", "New")
 	var isTestingError bool
 	se, ok := ce.Fun.(*ast.SelectorExpr)
 	if ok && se.Sel.Name == "Error" {
@@ -60,7 +61,7 @@ func (w lintErrorf) Visit(n ast.Node) ast.Visitor {
 	}
 	arg := ce.Args[0]
 	ce, ok = arg.(*ast.CallExpr)
-	if !ok || !isPkgDot(ce.Fun, "fmt", "Sprintf") {
+	if !ok || !astutils.IsPkgDotName(ce.Fun, "fmt", "Sprintf") {
 		return w
 	}
 	errorfPrefix := "fmt"

rule/flag_param.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"go/ast"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -26,7 +27,7 @@ func (*FlagParamRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure {
 
 		boolParams := map[string]struct{}{}
 		for _, param := range fd.Type.Params.List {
-			if !isIdent(param.Type, "bool") {
+			if !astutils.IsIdent(param.Type, "bool") {
 				continue
 			}
 
@@ -77,7 +78,7 @@ func (w conditionVisitor) Visit(node ast.Node) ast.Visitor {
 		return w.idents[ident.Name] == struct{}{}
 	}
 
-	uses := pick(ifStmt.Cond, findUsesOfIdents)
+	uses := astutils.PickNodes(ifStmt.Cond, findUsesOfIdents)
 
 	if len(uses) < 1 {
 		return w

rule/identical_branches.go

@@ -3,6 +3,7 @@ package rule
 import (
 	"go/ast"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -64,12 +65,12 @@ func (*lintIdenticalBranches) identicalBranches(branches []*ast.BlockStmt) bool
 		return false // only one branch to compare thus we return
 	}
 
-	referenceBranch := gofmt(branches[0])
+	referenceBranch := astutils.GoFmt(branches[0])
 	referenceBranchSize := len(branches[0].List)
 	for i := 1; i < len(branches); i++ {
 		currentBranch := branches[i]
 		currentBranchSize := len(currentBranch.List)
-		if currentBranchSize != referenceBranchSize || gofmt(currentBranch) != referenceBranch {
+		if currentBranchSize != referenceBranchSize || astutils.GoFmt(currentBranch) != referenceBranch {
 			return false
 		}
 	}

rule/modifies_value_receiver.go

@@ -5,6 +5,7 @@ import (
 	"go/token"
 	"strings"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -116,7 +117,7 @@ func (r *ModifiesValRecRule) findReturnReceiverStatements(receiverName string, t
 		return false
 	}
 
-	return pick(target, finder)
+	return astutils.PickNodes(target, finder)
 }
 
 func (r *ModifiesValRecRule) mustSkip(receiver *ast.Field, pkg *lint.Package) bool {
@@ -179,5 +180,5 @@ func (r *ModifiesValRecRule) getReceiverModifications(receiverName string, funcB
 		return false
 	}
 
-	return pick(funcBody, receiverModificationFinder)
+	return astutils.PickNodes(funcBody, receiverModificationFinder)
 }

rule/optimize_operands_order.go

@@ -5,6 +5,7 @@ import (
 	"go/ast"
 	"go/token"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -63,20 +64,20 @@ func (w lintOptimizeOperandsOrderExpr) Visit(node ast.Node) ast.Visitor {
 	}
 
 	// check if the left sub-expression contains a function call
-	nodes := pick(binExpr.X, isCaller)
+	nodes := astutils.PickNodes(binExpr.X, isCaller)
 	if len(nodes) < 1 {
 		return w
 	}
 
 	// check if the right sub-expression does not contain a function call
-	nodes = pick(binExpr.Y, isCaller)
+	nodes = astutils.PickNodes(binExpr.Y, isCaller)
 	if len(nodes) > 0 {
 		return w
 	}
 
 	newExpr := ast.BinaryExpr{X: binExpr.Y, Y: binExpr.X, Op: binExpr.Op}
 	w.onFailure(lint.Failure{
-		Failure:    fmt.Sprintf("for better performance '%v' might be rewritten as '%v'", gofmt(binExpr), gofmt(&newExpr)),
+		Failure:    fmt.Sprintf("for better performance '%v' might be rewritten as '%v'", astutils.GoFmt(binExpr), astutils.GoFmt(&newExpr)),
 		Node:       node,
 		Category:   lint.FailureCategoryOptimization,
 		Confidence: 0.3,

rule/range.go

@@ -5,6 +5,7 @@ import (
 	"go/ast"
 	"strings"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -43,7 +44,7 @@ func (w *lintRanges) Visit(node ast.Node) ast.Visitor {
 		// for x = range m { ... }
 		return w // single var form
 	}
-	if !isIdent(rs.Value, "_") {
+	if !astutils.IsIdent(rs.Value, "_") {
 		// for ?, y = range m { ... }
 		return w
 	}

rule/struct_tag.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 
 	"github.com/fatih/structtag"
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -390,7 +391,7 @@ func checkCompoundPropertiesOption(key, value string, fieldType ast.Expr, seenOp
 			return msgTypeMismatch, false
 		}
 	case "layout":
-		if gofmt(fieldType) != "time.Time" {
+		if astutils.GoFmt(fieldType) != "time.Time" {
 			return "layout option is only applicable to fields of type time.Time", false
 		}
 	}

rule/time_date.go

@@ -8,6 +8,7 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 	"github.com/mgechev/revive/logging"
 )
@@ -61,7 +62,7 @@ func (w lintTimeDate) Visit(n ast.Node) ast.Visitor {
 	if !ok || len(ce.Args) != timeDateArity {
 		return w
 	}
-	if !isPkgDot(ce.Fun, "time", "Date") {
+	if !astutils.IsPkgDotName(ce.Fun, "time", "Date") {
 		return w
 	}
 

rule/time_equal.go

@@ -5,6 +5,7 @@ import (
 	"go/ast"
 	"go/token"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -66,7 +67,7 @@ func (l *lintTimeEqual) Visit(node ast.Node) ast.Visitor {
 		Category:   lint.FailureCategoryTime,
 		Confidence: 1,
 		Node:       node,
-		Failure:    fmt.Sprintf("use %s%s.Equal(%s) instead of %q operator", negateStr, gofmt(expr.X), gofmt(expr.Y), expr.Op),
+		Failure:    fmt.Sprintf("use %s%s.Equal(%s) instead of %q operator", negateStr, astutils.GoFmt(expr.X), astutils.GoFmt(expr.Y), expr.Op),
 	})
 
 	return l

rule/unchecked_type_assertion.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"go/ast"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -70,12 +71,7 @@ type lintUncheckedTypeAssertion struct {
 }
 
 func isIgnored(e ast.Expr) bool {
-	ident, ok := e.(*ast.Ident)
-	if !ok {
-		return false
-	}
-
-	return ident.Name == "_"
+	return astutils.IsIdent(e, "_")
 }
 
 func isTypeSwitch(e *ast.TypeAssertExpr) bool {
@@ -177,7 +173,7 @@ func (w *lintUncheckedTypeAssertion) Visit(node ast.Node) ast.Visitor {
 }
 
 func (w *lintUncheckedTypeAssertion) addFailure(n *ast.TypeAssertExpr, why string) {
-	s := fmt.Sprintf("type cast result is unchecked in %v - %s", gofmt(n), why)
+	s := fmt.Sprintf("type cast result is unchecked in %v - %s", astutils.GoFmt(n), why)
 	w.onFailure(lint.Failure{
 		Category:   lint.FailureCategoryBadPractice,
 		Confidence: 1,

rule/unconditional_recursion.go

@@ -3,6 +3,7 @@ package rule
 import (
 	"go/ast"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -174,7 +175,7 @@ func (*lintUnconditionalRecursionRule) hasControlExit(node ast.Node) bool {
 		case *ast.ReturnStmt:
 			return true
 		case *ast.CallExpr:
-			if isIdent(n.Fun, "panic") {
+			if astutils.IsIdent(n.Fun, "panic") {
 				return true
 			}
 			se, ok := n.Fun.(*ast.SelectorExpr)
@@ -197,5 +198,5 @@ func (*lintUnconditionalRecursionRule) hasControlExit(node ast.Node) bool {
 		return false
 	}
 
-	return len(pick(node, isExit)) != 0
+	return len(astutils.PickNodes(node, isExit)) != 0
 }

rule/unhandled_error.go

@@ -8,6 +8,7 @@ import (
 	"regexp"
 	"strings"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -122,7 +123,7 @@ func (w *lintUnhandledErrors) addFailure(n *ast.CallExpr) {
 func (w *lintUnhandledErrors) funcName(call *ast.CallExpr) string {
 	fn, ok := w.getFunc(call)
 	if !ok {
-		return gofmt(call.Fun)
+		return astutils.GoFmt(call.Fun)
 	}
 
 	name := fn.FullName()

rule/unnecessary_format.go

@@ -94,7 +94,7 @@ func (w lintUnnecessaryFormat) Visit(n ast.Node) ast.Visitor {
 		return w
 	}
 
-	funcName := gofmt(ce.Fun)
+	funcName := astutils.GoFmt(ce.Fun)
 	spec, ok := formattingFuncs[funcName]
 	if !ok {
 		return w
@@ -110,7 +110,7 @@ func (w lintUnnecessaryFormat) Visit(n ast.Node) ast.Visitor {
 		return w
 	}
 
-	format := gofmt(arg)
+	format := astutils.GoFmt(arg)
 
 	if strings.Contains(format, `%`) {
 		return w

rule/unused_param.go

@@ -5,6 +5,7 @@ import (
 	"go/ast"
 	"regexp"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -122,7 +123,7 @@ func (w lintUnusedParamRule) Visit(node ast.Node) ast.Visitor {
 
 		return false
 	}
-	_ = pick(funcBody, fselect)
+	_ = astutils.PickNodes(funcBody, fselect)
 
 	for _, p := range funcType.Params.List {
 		for _, n := range p.Names {

rule/unused_receiver.go

@@ -5,6 +5,7 @@ import (
 	"go/ast"
 	"regexp"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -82,7 +83,7 @@ func (r *UnusedReceiverRule) Apply(file *lint.File, _ lint.Arguments) []lint.Fai
 
 			return isAnID && ident.Obj == recID.Obj
 		}
-		receiverUses := pick(funcDecl.Body, selectReceiverUses)
+		receiverUses := astutils.PickNodes(funcDecl.Body, selectReceiverUses)
 
 		if len(receiverUses) > 0 {
 			continue // the receiver is referenced in the func body

rule/use_errors_new.go

@@ -3,6 +3,7 @@ package rule
 import (
 	"go/ast"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -39,7 +40,7 @@ func (w lintFmtErrorf) Visit(n ast.Node) ast.Visitor {
 		return w // not a function call
 	}
 
-	isFmtErrorf := isPkgDot(funcCall.Fun, "fmt", "Errorf")
+	isFmtErrorf := astutils.IsPkgDotName(funcCall.Fun, "fmt", "Errorf")
 	if !isFmtErrorf {
 		return w // not a call to fmt.Errorf
 	}

rule/utils.go

@@ -1,10 +1,7 @@
 package rule
 
 import (
-	"bytes"
 	"fmt"
-	"go/ast"
-	"go/printer"
 	"go/token"
 	"regexp"
 	"strings"
@@ -26,31 +23,6 @@ var exitFunctions = map[string]map[string]bool{
 	},
 }
 
-func isCgoExported(f *ast.FuncDecl) bool {
-	if f.Recv != nil || f.Doc == nil {
-		return false
-	}
-
-	cgoExport := regexp.MustCompile(fmt.Sprintf("(?m)^//export %s$", regexp.QuoteMeta(f.Name.Name)))
-	for _, c := range f.Doc.List {
-		if cgoExport.MatchString(c.Text) {
-			return true
-		}
-	}
-	return false
-}
-
-func isIdent(expr ast.Expr, ident string) bool {
-	id, ok := expr.(*ast.Ident)
-	return ok && id.Name == ident
-}
-
-// isPkgDot checks if the expression is <pkg>.<name>
-func isPkgDot(expr ast.Expr, pkg, name string) bool {
-	sel, ok := expr.(*ast.SelectorExpr)
-	return ok && isIdent(sel.X, pkg) && isIdent(sel.Sel, name)
-}
-
 func srcLine(src []byte, p token.Position) string {
 	// Run to end of line in both directions if not at line start/end.
 	lo, hi := p.Offset, p.Offset+1
@@ -63,48 +35,6 @@ func srcLine(src []byte, p token.Position) string {
 	return string(src[lo:hi])
 }
 
-// pick yields a list of nodes by picking them from a sub-ast with root node n.
-// Nodes are selected by applying the fselect function
-func pick(n ast.Node, fselect func(n ast.Node) bool) []ast.Node {
-	var result []ast.Node
-
-	if n == nil {
-		return result
-	}
-
-	onSelect := func(n ast.Node) {
-		result = append(result, n)
-	}
-	p := picker{fselect: fselect, onSelect: onSelect}
-	ast.Walk(p, n)
-	return result
-}
-
-type picker struct {
-	fselect  func(n ast.Node) bool
-	onSelect func(n ast.Node)
-}
-
-func (p picker) Visit(node ast.Node) ast.Visitor {
-	if p.fselect == nil {
-		return nil
-	}
-
-	if p.fselect(node) {
-		p.onSelect(node)
-	}
-
-	return p
-}
-
-// gofmt returns a string representation of an AST subtree.
-func gofmt(x any) string {
-	buf := bytes.Buffer{}
-	fs := token.NewFileSet()
-	printer.Fprint(&buf, fs, x)
-	return buf.String()
-}
-
 // checkNumberOfArguments fails if the given number of arguments is not, at least, the expected one
 func checkNumberOfArguments(expected int, args lint.Arguments, ruleName string) error {
 	if len(args) < expected {

rule/var_declarations.go

@@ -7,6 +7,7 @@ import (
 	"go/types"
 	"strings"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -79,14 +80,14 @@ func (w *lintVarDeclarations) Visit(node ast.Node) ast.Visitor {
 		rhs := v.Values[0]
 		// An underscore var appears in a common idiom for compile-time interface satisfaction,
 		// as in "var _ Interface = (*Concrete)(nil)".
-		if isIdent(v.Names[0], "_") {
+		if astutils.IsIdent(v.Names[0], "_") {
 			return nil
 		}
 		// If the RHS is a isZero value, suggest dropping it.
 		isZero := false
 		if lit, ok := rhs.(*ast.BasicLit); ok {
 			isZero = isZeroValue(lit.Value, v.Type)
-		} else if isIdent(rhs, "nil") {
+		} else if astutils.IsIdent(rhs, "nil") {
 			isZero = true
 		}
 		if isZero {
@@ -122,7 +123,7 @@ func (w *lintVarDeclarations) Visit(node ast.Node) ast.Visitor {
 			return nil
 		}
 		// If the RHS is an untyped const, only warn if the LHS type is its default type.
-		if defType, ok := w.file.IsUntypedConst(rhs); ok && !isIdent(v.Type, defType) {
+		if defType, ok := w.file.IsUntypedConst(rhs); ok && !astutils.IsIdent(v.Type, defType) {
 			return nil
 		}
 

rule/var_naming.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -267,7 +268,7 @@ func (w *lintNames) Visit(n ast.Node) ast.Visitor {
 		// Exclude naming warnings for functions that are exported to C but
 		// not exported in the Go API.
 		// See https://github.com/golang/lint/issues/144.
-		if ast.IsExported(v.Name.Name) || !isCgoExported(v) {
+		if ast.IsExported(v.Name.Name) || !astutils.IsCgoExported(v) {
 			w.check(v.Name, thing)
 		}
 

rule/waitgroup_by_value.go

@@ -3,6 +3,7 @@ package rule
 import (
 	"go/ast"
 
+	"github.com/mgechev/revive/internal/astutils"
 	"github.com/mgechev/revive/lint"
 )
 
@@ -40,7 +41,7 @@ func (w lintWaitGroupByValueRule) Visit(node ast.Node) ast.Visitor {
 
 	// Check all function parameters
 	for _, field := range fd.Type.Params.List {
-		if !w.isWaitGroup(field.Type) {
+		if !astutils.IsPkgDotName(field.Type, "sync", "WaitGroup") {
 			continue
 		}
 
@@ -53,14 +54,3 @@ func (w lintWaitGroupByValueRule) Visit(node ast.Node) ast.Visitor {
 
 	return nil // skip visiting function body
 }
-
-func (lintWaitGroupByValueRule) isWaitGroup(ft ast.Expr) bool {
-	se, ok := ft.(*ast.SelectorExpr)
-	if !ok {
-		return false
-	}
-
-	x, _ := se.X.(*ast.Ident)
-	sel := se.Sel.Name
-	return x.Name == "sync" && sel == "WaitGroup"
-}

testdata/unnecessary_stmt.go

@@ -1,5 +1,11 @@
 package fixtures
 
+import (
+	ast "go/ast"
+
+	"github.com/mgechev/revive/lint"
+)
+
 func foo(a, b, c, d int) {
 	switch n := node.(type) { // MATCH /switch with only one case can be replaced by an if-then/
 	case *ast.SwitchStmt:
@@ -7,7 +13,7 @@ func foo(a, b, c, d int) {
 			_, ok := n.(*ast.CaseClause)
 			return ok
 		}
-		cases := pick(n.Body, caseSelector, nil)
+		cases := astutils.PickNodes(n.Body, caseSelector, nil)
 		if len(cases) == 1 {
 			cs, ok := cases[0].(*ast.CaseClause)
 			if ok && len(cs.List) == 1 {